Bisorganophosphorus esters and their preparation



Unite 3,100,735 BISORGANOPHOSPHORUS ESTERS AND THEIR PREPARATION Karoly Szabo, Yonkers, N.Y., and John G. Brady, Campbell, Calif., assignors to Stauifer Chemical Company,

New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 7, 1961, Ser. No. 150,625

1 8 Ciaims. (Cl. 167-22) wherein R and R refer to lower alkyl radicals preferably those having from 1 to 4 carbon atoms and n is an integer of from 1 to 2. The alkyl groups include both normal and branch chains and may be alike or different. Illustrative compounds falling within the ambit of the above depicted formula include. the following specific structures:

dihhfldfi Patented Aug. 13, 1963 Compound 8 The bisorganophosphorus esters of this invention are susceptible to a generalized method of preparation which comprises condensing, preferably in the presence of a basic condensing agent, about one mole of a dihalodialkylsulfide of the following formula:

wherein n has the significance previously designated and X represents a halogen atom, i.e. chlorine, bromine and the like with about 2 moles of a lower alkyl ester of phosphonodithioic acid. The reaction is schematically indicated by the following equation:

wherein X, R, R and n have the meaning previously defined. It has been our finding that generally excellent results and yields are obtained by'heating the phosphonodithioic acid and dihalodialkylsulfide in approximately 2 to 1 molar ratios in a relatively inert normally liquid organic solvent in the presence of a tertiary amine as the basic condensing agent. Suitable solvent mediums are exemplified by liquid aromatic hydrocarbons such as benzene, toluene, Xylene etc., saturated aliphatic hydrocarbons such as hexane, heptane, cyclohexane etc. and saturated aliphatic ethers. Basic condensing agents which have been found satisfactory for effecting the reaction include basic organic amines, preferably tertiary amines as represented by the lower trialkylarnines, e.g. trirnethylamine, triethylamine etc., tertiary heterocyclic amines such aspyridine, picoline, quinoline, etc., inorganic bases and basic salts, e.g. alkali metal carbonates, e.g. sodium carbonate, potassium carbonate and the like. In some instances the reaction is advantageously performed ina medium capable of functioning both as a solvent and as the basic condensing agent. Pyridine and quinoline are examples of such dual purpose solvents.

Reference is now made to the following examples which are presented for the purpose of illustration only since variations in practicing the invention without departing from the spirit or scope thereof will be apparent to those skilled in the art to which the said invention pertains.

g. An exothermic reaction occurred and the temperature rose to 55 C. After the temperature began to drop,

refluxing was maintained for 10 minutes after which the triethylamine hydrochloride was filtered off and the filtrate washed with 1% sodium hydroxide solution and then with water. The organic layer was dried over anhydrous magnesium sulfate and the solvent removed under reduced pressure. The residue was a light yellow oil having a refractive index of 1.5625. The chemical analysis of the product conformed to the above depicted formula.

EXAMPLE 2 In this preparation, the procedure of the first example was carried out but substituting equivalent quantities of O-methyl ethylphosphonodithioic acid in lieu of the corresponding O-ethyl ethylphosphonodithioic acid of the previous example. In general, the yields and results fell in line with those obtained in the case of Example 1. The product, in this instance, was a slightly yellow oil having a refractive index of 1.5674.

EXAMPLE 3 C2H O S V S OCsH5 Using the procedure of Example 1, 1 mole of bischloromethylsulfide was reacted with 2 moles of O-ethyl chloromethylphosphonodithioic acid. The results and yields were inline with those obtained in the case of the earlier examples. The chemical analysis of the product agreed with the abovev depicted formula.

As' stated elsewhere herein, the organophosphorus esters of this invention are eminently useful and suitable for combating a variety of pests of the type which fall in the lower orders of classification and which are exemplified'by cockroaches, milkweed bugs, confused flour beetles, house flies, two-spotted mites and the like. It is to be understood that the toxicants of the invention may be used directly on the adult pest organism or applied to the eggs. In either case, the end result is to eradicate or control the pest organism.

' As those in the art are well aware, various techniques are available for incorporating the active component or toxicant in suitable pesticidal compositions. Thus pesticidal compositions can be conveniently prepared in the form of liquids or solids, the latter preferably as homogeneous free-flowing dusts commonly formulated by admixing the active component with finely divided solids or carriers as exemplified by talc, natural clays, diatomaceons earth, various flours such as walnut shell, Wheat, soya bean, cotton seed and so forth.

Liquid compositions are also useful and normally comprise a dispersion of the toxicant in a liquid media. For

instance, it may be convenient to dissolve thestoxicant 4, directly in a solvent such as kerosene, fuel oil, xylene, alkylated naphthalenes or the like and use such organic solutions directly. However, it is more common procedure to employ dispersion of the toxicant in an aqueous media and such compositions may be produced by forming a concentrated solution of the toxicant in a suitable organic solvent followed by dispersion in water, usually with the aid of surface active agents. The latter, which may be the anionic, cationic or nonionic types, are exemplified by sodium stearate, potassium oleate and other alkaline metal soaps and detergents such as sodium lauryl sulfate, sodium naphthalene, sulfon'ate, sodium alkyl naphthalene sulfonate, methyl cellulose, polyoxyethylene, fatty alcohol ethers, polyglycol fatty acid esters and other polyoxyethylene surface active agents. The proportion of these agents commonly comprises 1-15 by weight of the pesticidal compositions although the proportion is not critical and may be varied to suit any particular situation.

Other adjuncts may be resorted to in compounding biocidal formulations based on the herein described organophosphorus esters and, in this connection, reference is made to adhesives, spreaders, activators, fertilizers and the like. The preparation of pesticidal compositions incorporating the organophosphorus esters of this invention and the results of testing such compositions are spelled out in the following test procedures:

Acaricidal evaluation test-The two-spotted mite, Tetranychus telarius (Linn), is employed in tests for acaricide's. Young pinto bean plants are infested with several hundred mites. Dispersions of test compounds are prepared by dissolving 0.1 gram of the toxic material in ten milliliters acetone. This solution is then diluted with water containing00l5 Vatsol (sodium salt of isopropyl naphthalene sulfonate) and 0.005% Methocel (methylated cellulose) as emulsifiers, the amount of Water being suflicient to give concentrations of active ingredient ranging from 0.25% to 0.005%. The test suspensions are then sprayed onthe infested pinto bean plants. After seven and fourteen days, the plants are examined both for post-embryonic forms of the mite as well as eggs. The percentage of kill is determined by comparison with control plants which have not been sprayed and the LD-50 value calculated using well-known procedures. LD-50 values are reported under the columns 2-sp0tted mite and 2-spotted mite eggs on the table below.

Insecticidal evaluation tests.--'Four insect species are subjected to evaluation tests for insecticides:

(1) American cockroach (AR), Periplanela americana (Linn) (2) Milkweed bug (MWB), Oncopeltus fasciatus (Dal (3) Confused flour beetle (CFB), Tribolium' confusam (Duvial) (4) House fly (HF), Musca domestica (Linn) The procedure for insects is similar to the miticidal testing procedure. mailing tubes 3% in diameter and 2 /8 tall. The cages are supplied with cellophane bottoms and screened tops. Ten to twenty-five insects are used per cage. Food and water are supplied in each cage. The confused flour beetles are confined in petri dishes without food. The caged insects are sprayed with the active compound at various concentrations. After twenty-four and seventytwo hours, counts are made to determine living and dead insects.

House fly evaluation tests differ in this respect: the toxicant is dissolved in a volatile solvent, preferably acetone, the active compound is pipetted into a petri dish bottom, allowed to air dry and placed in the cardboard mailing tube. Twenty-five female flies are caged in the tube. The flies are continuously exposed to the known residue of the active compound in the cage. After twenty-four and forty-eight hours, counts are made to determine living and dead insects. he LD-SO values are Test insects are caged in cardboard calculated using well-known the table below.

procedures, and reported in Table Ameri- Milk- Con- 2-spotted Salt Com- House can weed fused 2-spotted mite arsh Z-spotted pound fiy, roach, bug, flour mite, eggs, cater- 1 m e pg. percent percent beetle, percent percent pillar, systemic,

pg. percent p.p.m.

We claim: ganophosphorus ester having the following general 1. A bisorganophosphorus ester of the following genformula: eral formula: S

H ll S R-]iS(OHa)nS(CH1)nSP-R II II a-r-s-wnon-som)n-s-P-R B1 A wherem R and R represent lower alkyl radicals and n 3. A bisorganophosphorus .ester of the atoll-owing formula: 1

4. A bisorlganophosphorus ester of the following formula:

5. A method of killing pests which comprises applying to a pest habitat a small but effective amount of a bisoris an integer of from 1 to 2.

6. A method of killing pests which comprises applying to a pest habitat a small but efiective amount of a bisorganophosphorous ester of the following formula:

7. A method of killing pests which eomprisesapplying to a pest habitat a small but reflective amount of a hisorganophosphorus ester of the following formula:

8. A method of killing pests which comprises applying to a pest habitat a small but effective amount of a bisorganophosphorus ester of the following formula:

France Oct. 15, 1959 

5. A METHOD OF KILLING PESTS WHICH COMPRISES APPLYING TO A PEST HABITAT A SMALL BUT EFFECTIVE AMOUNT OF A BISORGANOPHOSPHORUS ESTER HAVING THE FOLLOWING GENERAL FORMULA: 